Lithographic printing plate precursor

1. A lithographic printing plate precursor comprising a substrate having thereon in order an interlayer containing a copolymer comprising K units and L units, and an image-forming layer that comprises a photothermal conversion material, wherein

said K unit is derived from a monomer of the formula I:

wherein R 1 represents a hydrogen atom, a C 1-22 linear, branched or cyclic alkyl group, a C 1-22 linear, branched or cyclic, substituted alkyl group, a C 6-24 aryl group or substituted aryl group, wherein the substituent on the substituted alkyl or aryl group is selected from a C 1-4 alkyl group, an aryl group, a halogen atom, a keto group, an ester group, an alkoxy group, or a cyano group; Y 1 represents an alkyleneoxyalkylene or poly(alkyleneoxy)alkylene group having 2 or 3 carbon atoms in the alkylene group; or

from the monomer CH 2 ═CHPO(OH) 2 ; and

said L unit is derived from a monomer of the formula II:

CH 2 ═CRCONH 2   (II)

wherein R is H or CH 3 , and

said K units are present in the copolymer in an amount of from more than 3% and less than 40% and said L units are present in the copolymer in an amount of from more than 60% and less than 97%, both based on the total moles of recurring units in the copolymer.

2. The lithographic printing plate precursor according to claim 1 , wherein the copolymer further comprises units derived from a monomer containing an onium group or a monomer containing a sulfonic acid group.

3. The lithographic printing plate precursor according to claim 1 , wherein the substrate is a roughened sulfuric acid-anodized aluminum substrate.

4. The lithographic printing plate precursor according to claim 1 , wherein the K units are derived from a monomer selected from the group consisting of vinyl phosphonic acid and ethylene glycol methacrylate phosphate, and the L units are derived from a monomer selected from the group consisting of acrylamide and methacrylamide.

5. The lithographic printing plate precursor according to claim 1 , wherein the image-forming layer is a positive working image-forming layer.

6. The lithographic printing plate precursor according to claim 1 , wherein the image-forming layer is a negative working image-forming layer.

7. The lithographic printing plate precursor of claim 1 , wherein the K units are present in an amount of at least 3% to 35%, and the L units are present in an amount of at least 65% to 95%, based on the total moles of recurring units in the copolymer.

8. The lithographic printing plate precursor of claim 1 that is positive-working and comprises two image-forming layers disposed over the interlayer.

9. The lithographic printing plate precursor of claim 1 , wherein the image-forming layer is an on-press developable negative-working image-forming layer.

10. The lithographic printing plate precursor of claim 1 , wherein the image-forming layer comprises an infrared radiation sensitive dye.

11. The lithographic printing plate precursor of claim 1 , wherein the interlayer is present at a coverage of 5 mg/m 2 to 40 mg/m 2 based on dry mass.

12. The lithographic printing plate precursor of claim 1 , wherein the interlayer further comprises sulfuric acid, phosphoric acid, an organic acid, poly(methacrylic acid), or an inorganic salt.

13. The lithographic printing plate precursor of claim 1 , wherein the interlayer comprises the copolymer that comprises:

K units derived from one or more of vinyl phosphonic acid, ethylene glycol acrylate phosphate, ethylene glycol methacrylate phosphate, polyethylene glycol acrylate phosphate, polyethylene glycol methacrylate phosphate, polypropylene glycol acrylate phosphate, and polypropylene glycol methacrylate phosphate, and

L units derived from acrylamides or methacrylamide.

14. The lithographic printing plate precursor of claim 13 , wherein the K units are present in the copolymer in an amount of from 10% to 35%, and the L units are present in the copolymer in an amount of from 65% to 90%, based on total moles of recurring units in the copolymer.

15. The lithographic printing plate precursor of claim 13 , wherein the copolymer further comprises 1% to 2%, based on total moles of recurring units, of one or more of 3-(acrylamidepropyl)trimethylammonium chloride, diaryldimethylammonium chloride, methacryloylcholine chloride, aryl sulfonic acid, styrenesulfonic acid, and 2-acrylamide-2-methylpropanesulfonic acid.

16. The lithographic printing plate precursor of claim 1 , wherein the image-forming layer further comprises an aqueous alkali soluble or dispersible resin.

17. A method for forming a lithographic printing plate, comprising:

imagewise exposing the lithographic printing plate precursor of claim 1 that is a positive-working lithographic printing plate precursor to provide exposed areas and non-exposed areas in the image-forming layer, and

removing the exposed areas in the image-forming layer.

18. The method of claim 17 comprising imagewise exposing the lithographic printing plate precursor using an infrared radiation laser.

19. The method of claim 17 , comprising removing the exposed areas of the image-forming layer with an aqueous alkali solution.